I propose to investigate and compare the rate and pattern of degradation of liver mitochondria of healthy animals to that of diabetic animals and cultured liver hepatocytes. My attention will focus primarily upon the degradative rates of representative mitochondrial enzymes from both the soluble and membrane compartments and initially with in vivo evaluation of these rats in normal rats. This baseline information will determine whether mitochondria are degraded piecemeal as individual components by specific mitochondrial proteinases, each component having its own characteristic half life, or whether they are degraded as intact units by a lysosomal derived autophagous system. Identical degradative rates for each membrane enzyme and its component polypeptides would indicate a role of lysosomes in regulating mitochondria number, while distinctly heterogeneous rates of degradation for each enzyme or its component subunits would support the role of non-lysosomal, intra-mitochondrial proteinases in regulating mitochondrial protein content. The determined rates and pattern of mitochondrial polypeptide degradation in healthy animals will be further used as a probe to determine the mechanism of increased protein degradation in diabetic animals. If decreased insulin levels stimulate to identical rates the degradation of mitochondria and its selected component proteins, it would indicate a direct effect of the diabetic condition on lysosomal activity. Lastly, information regarding the intracellular site and rate of degradation of mitochondrial polypeptides in animals will be used as a baseline to examine protein metabolism outside of the animal in isolated, cultured liver hepatocytes. Favorable comparison of the rates and pattern of mitochondrial protein degradation in cultured hepatocytes to that found in whole animals would proffer these cells as an in vitro system to examine protein degradation and its regulation in mitochondria and perhaps other cellular compartments.